The manufacturing properties of thermoplastic polymers, for example the extruding properties of such polymers, is often modified/enhanced by the addition of plasticisers thereto. As acknowledged in the prior art, such as in U.S. Pat. No. 4,426,477, there is a tendency toward avoiding the commonly used plasticisers such as dioctyl adipate (DOA) and phthalate plasticisers such as dioctyl phthalate (DOP). The safety of these plasticisers has been called into question, particularly in certain applications.
U.S. Pat. No. 4,426,477 discloses plasticisers based on glycerol esters. The plasticisers consist of compounds prepared by the acylation of glycerol. The compounds comprises triesters, wherein approximately two of the acyls have two carbons and the remaining one acyl has from 10 to 14 carbons. The compounds of U.S. Pat. No. 4,426,477 provide a plasticising effect. However, in certain applications the plasticisers have a volatility such that they may migrate out of the thermoplastic polymer in which they are incorporated, such as PVC.
In a first aspect the present invention provides a composition comprising i) a thermoplastic polymer ii) a compound having the formula 
wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom, wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 6 carbon atoms, wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of or having a saturated chain having 10 to 20 carbon atoms and a hydrophilic branch group.
Preferably two of R1, R2 and R3 are short acyl groups as described above and the other of R1, R2 and R3 is a long acyl group as described above. In this aspect, the compound may be of the formula 
Preferably the hydrophilic branch group is a group selected from acyl and derivatives thereof. Preferred derivatives include groups of the formula xe2x80x94O-acyl.
Preferably the hydrophilic branch group is a group of the formula 
wherein p is from 0 to 4 or 0 to 3.
In a preferred aspect of the present invention the chain of the long acyl group consists of or has a saturated chain having 14 to 20 carbon atoms. In a more preferred aspect, the chain of the long acyl group consists of or has a saturated chain having 16 to 20 carbon atoms
Preferably the long acyl group is of the formula 
wherein n is from 10 to 20 and m is 2n, and wherein p is from 0 to 4 or 0 to 3.
Preferably n is from 16 to 20, more preferably from 16 to 18, yet more preferably 17.
Preferably the group CnHm is a straight chain hydrocarbon group.
In a highly preferred aspect the long acyl group is a group of the formula 
wherein x is from 7 to 10, preferably x is 10, and y is 2x, and wherein p is from 0 to 4 or 0 to 3, preferably p is 0.
Preferably the group CxHy is or comprises a straight chain hydrocarbon group.
In a highly preferred aspect the long acyl group is a group of the formula 
In a preferred aspect of the present invention the short acyl group is or comprises an acyl group having from 2 to 5 carbon atoms. In a more preferred aspect, the short acyl group is or comprises an acyl group having 2 carbon atoms. The short acyl group is preferably of the formula 
Preferably the short acyl group and the hydrophilic branch group contain the same number of carbon atoms. In a highly preferred aspect the hydrophilic branch group is a group of the formula 
and the short acyl group is of the formula 
wherein p=q and is from 0 to 4 or 0 to 3.
In certain aspects, it is desirable for the short acyl groups to be present in a maximum amount with respect to the total amount glycerol and esters thereof present in the composition. Preferably the short acyl group is present in an amount on average, of no greater than 2 moles per mole of glycerol and esters thereof present in the composition.
In certain aspects, it is desirable for the long acyl groups to be present in a minimum amount with respect to the total amount glycerol and esters thereof present in the composition. Preferably the long acyl group is present in an amount, on average, of at least 0.4 moles, preferably from 0.9 to 2 moles, more preferably from 0.9 to 1 moles per mole of glycerol and esters thereof present in the composition.
It may also be preferred for the majority of the glycerol present in the composition to be fully acylated Accordingly, in a preferred aspect the total amount of acyl groups is, on average, 2.7 to 3.0 moles per mole of glycerol and esters thereof
The compound of the present invention may be prepared by interesterification between glycerol and one or more oils, including natural oils and hardened natural oils followed by acylation. Thus, the compound of the present invention may be the product of a two part process comprising (i) an interesterification between glycerol and an oil selected from castor oil, including hardened castor oil, unhardened castor oil and mixtures thereof, and (ii) acylation.
Thus in a further aspect the present invention provides a process for the preparation of a compound having the formula 
wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom; wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 6 carbon atoms or from 2 to 5 carbons; wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of or having a chain having 10 to 20 carbon atoms and a hydrophilic branch group; the process comprising the steps of:
(i) interesterification between glycerol and triglyceride compound having the formula 
wherein each of R1, R2 and R3 is a fatty acid group consisting of or having a chain having 10 to 20 carbon atoms, to provide a composition comprising glycerol, monoglyceride, diglyceride and/or triglyceride;
(ii) optionally isolating the monoglyceride and/or diglyceride from the composition;
(iii) acylating the monoglyceride and/or diglyceride or the composition containing the same.
In the process of the present invention the chain having 10 to 20 carbon may be saturated or unsaturated.
The process of the present invention may utilise, for example, castor oil or hardened castor oil. The compound of the present invention may be prepared from hardened castor oil. A typical fatty acid profile of castor oil and hardened castor oil is given below.
The nomenclature in parenthesis is Cxx:y where xx is the fatty acid carbon number and y indicates number of double bonds. Ricinoleic acid, hard (also known as 12-hydroxy stearic acid) has a hydroxyl group (OH) on the 12th carbon.
In this aspect the product based on the castor oil, or indeed a product based on another oil, may be synthesised as follows. These synthetic routes are given by way of example only. Other routes would be appreciated by a person skilled in the art
Route 1
Castor oil and glycerol are reacted to produce an equilibrium mixture of different glycerol esters. This mixture can be distilled and subsequently acetylated to provide the desired end products. This route is illustrated below. 
The second, step comprising the removal of the glycerol followed by distillation is optional. In other word the mixture of glycerol, glycerol monoester, glycerol diester, and glycerol triester may directly acetylated with acetic anhydride to form a mixture of acetylated products. The acetylated monoglyceride or the mixture of acetylated products may have a yellowish color. The yellowish product may be distilled. The distilled product is clear.
Depending on the ratio between castor oil and glycerol and depending on the reaction conditions, the described process provides different glycerol ester mixtures. The glycerol monoester is typically 45-65% and may be up to 65%. This is achieved in a typical reaction mixture. Such a composition may then, optionally, be fir processed to provide a product having a higher purity, for example a monoester content of above 90%.
Typical further processing would involve the removal of glycerol and the subsequent distillation of the resulting mixture. By means of this further processing an end product with a typical glycerol monoester content above 90% may be provided. The fatty acid profile of the end product would reflect the fatty acid profile of the castor oil stating material. This process, namely the production of a glycerol monoester, is described in Bailey""s Industrial Oil and Fat Products, vol. 4, Fifth ed. P.572 ff
The glycerol monoester may then be reacted with an excess of acetic anhydride resulting in acetic acid being esterified with the glycerol ester. Any excess of acetic anhydride is removed from the reaction mixture. The end product is a fully acetylated monoglyceride based on castor oil (which may be hardened or unhardened castor oil).
Route 2
Route 2 provides a further manner in which acetylated monoglycerides based on, for example, hardened and unhardened castor oil may be synthesised. An acetylated monoglyceride may be produced by the reaction of castor oil with acetic anhydride to provide an acetylated castor oil, The acetylated castor oil is then reacted with triacetin to produce acetylated monoglycerides based on hardened and unhardened castor oil. This process is illustrated below. 
Castor oil is reacted with acetic anhydride to produce an acetylated castor oil. The degree of acetylation may be defined as castor oil containing at least one acetic acid group and up to the average of three acetic acid groups per mole of castor oil. The acetylated castor oil is then reacted with triacetin to produce a reaction mixture of mainly acetylated glycerolesters with a fatty acid profile similar to that of the castor oil starting material. This mixture is purified by distillation. The end product is an acetylated monoglyceride based on hardened or unhardened castor oil.
A process for obtaining acetylated glycerol esters from the reaction of a triglyceride and triacetin is described in the Danish Patent No. 93 786. The synthesis of acetylated monoglycerides based on castor oil from the starting materials acetylated castor oil and triacetin is analogous to that process.
In a highly preferred aspect the compound of the present invention is selected from compounds of the formula 
These preferred compounds may be prepared and are preferably prepared in accordance with Route 1 or Route 2 above.
The above compounds are specific compounds which may be provided by the present invention. In a broad aspect, the present invention further provides a compound of the formula 
wherein two of R4, R5, and R6 are of the formula 
wherein for each of the two of R4, R5, and R6 q is independently selected from 0 to 4 or from 0 to 3; and the other of R4, R5, and R6 is a branched group of the formula 
wherein n is from 10 to 20 and m is 2 n, and wherein p is from 0 to 4 or from 0 to 3.
Preferably q is 0. More preferably for both of the two of R4, R5, and R6 q is 0.
Preferably n is from 16 to 20, more preferably from 16 to 18, yet more preferably 17.
Preferably the group CnHm is a straight chain hydrocarbon group.
In a preferred aspect the branched group is a group of the formula 
wherein x is from 7 to 10, preferably x is 10, and y is 2x, and wherein p is from 0 to 4 or from 0 to 3, preferably p is 0.
Preferably the group CxHy is a straight chain hydrocarbon group.
The compounds provided by the present invention may be incorporated in a composition comprising a thermoplastic polymer. Accordingly in a further aspect the present invention provides a composition comprising a compound as defined above and a thermoplastic polymer.
The thermoplastic polymer of the compositions of the present invention may be or comprise a vinyl chloride polymer or a vinyl chloride copolymer selected from vinyl chloride/vinyl acetate copolymer, vinyl chloride/vinylidene chloride copolymer, vinyl chloride/ethylene copolymer and a copolymer prepared by grafting vinyl chloride onto ethylene/vinyl acetate copolymer, or a mixture thereof.
In a preferred aspect the thermoplastic polymer is or comprises a polymer blend of a thermoplastic polymer, preferably a thermoplastic polymer as defined above, and a second polymer. Preferably, the second polymer is a methacryl polymer or an acrylonitrile-butadiene-styrene polymer.
The compositions of the present invention may be formulated in any manner to provide the required plasticising properties of the compound. In a particular aspect the composition of the present invention comprises the compound in an amount of 1 to 100 parts by weight per 100 parts by weight of the thermoplastic polymer.
As disclosed above the present invention provides a process for the preparation of a compound having the formula 
wherein R1, R2 and R3 are independently selected from an acyl group or a hydrogen atom, wherein at least one of R1, R2 and R3 is an acyl group (a short acyl group) having from 2 to 5 or from 2 to 6 carbon atoms, wherein at least one of R1, R2 and R3 is a branched chain acyl group (a long acyl group) consisting of or having a chain having 10 to 20 carbon atoms and a hydrophilic branch group, the process comprising the steps of: (i) interesterification between glycerol and triglyceride compound having the formula 
wherein each of R1, R2 and R3 is a fatty acid group consisting of or having a chain having 10 to 20 carbon atoms, to provide a composition comprising glycerol, monoglyceride, diglyceride and/or triglyceride; (ii) optionally isolating the monoglyceride and/or diglyceride from the composition; (iii) acylating the monoglyceride and/or diglyceride or the composition containing the same.
In the process of the present invention the chain having 10 to 20 carbon atoms may be saturated or unsaturated.
In preferred aspects the compound prepared by the process is a compound of the present invention as described herein. In a broader aspects
the long acyl group is of the formula 
wherein n is from 10 to 20 and m is selected from 2n, 2nxe2x88x922, 2nxe2x88x924 and 2nxe2x88x926, and wherein p is from 0 to 4 or from 0 to 3.
Preferably m is 2n or 2nxe2x88x922.
Preferably the group CnHm is a straight chain hydrocarbon group. The straight chain hydrocarbon group may be saturated or unsaturated. The straight chain hydrocarbon group may contain a single xe2x80x94Cxe2x95x90Cxe2x80x94 bond.
the long acyl group is a group of the formula 
wherein x is from 7 to 10, preferably x is 10, and y is 2xxe2x88x922, and wherein p is from 0 to 4 or from 0 to 3, preferably p is 0.
Preferably the group CxHy is a straight chain hydrocarbon group. The straight chain hydrocarbon group may be saturated or unsaturated. The straight chain hydrocarbon group may contain a single xe2x80x94Cxe2x95x90Cxe2x80x94 bond.
the long acyl group is a group of the formula 
the compound is of the formula 
the compound is of the formula 
wherein two of R4, R5, and R6 are of the formula 
wherein for each of the two of R4, R5, and R6 q is independently selected from 0 to 4 or from 0 to 3
and the other of R4, R5, and R6 is a branched group of the formula 
wherein n is from 10 to 20 and m is selected from 2n, 2nxe2x88x922, 2nxe2x88x924 and 2nxe2x88x926, and wherein p is from 0 to 4 or from 0 to 3. Preferably q is 0. More preferably for both of the two of R4, R5, and R6 q is 0. Preferably n is from 16 to 20, more preferably from 16 to 18, yet more preferably 17. Preferably m is 2nxe2x88x922.
the branched group is a group of the formula 
wherein x is from 7 to 10, preferably x is 10, and y is 2xxe2x80x942, and wherein p is from 0 to 4 or from 0 to 3, preferably p is 0.